The present invention relates to a stopcock with a plug which is rotary and adjustable in the cock housing. The stopcock bottom part has a fixedly mounted liner of elastic or flexible material with a smooth surface such as polytetrafluorethylene (PTFE) and is mounted in a rotary fashion, with a packing disk, which is clamped between inside and outside edge in the working area of a stopcock shank projecting to the outside and located between stopcock and housing. A gasket is located in a cylindrical annular space formed between the stopcock shank and a wall fixed to the housing. The reset force of a rest organ projecting into the annular space acts via the gasket and the packing disk on the stopcock bottom part for resetting the latter in its conical seat in the liner.
With a stopcock known from German Laid-Open Document No. 1,959,617, the stopcock shank protrudes through a ring-shaped housing cover to the outside and can be turned by a lever, a handwheel, etc. For sealing the cock housing from the stopcock shank, a packing disk is clamped between the housing and the ring cover. This packing disk extends to the inside up to a shoulder surface of the cock plug and is covered by a prop ring which permits resetting of the plug in relation to its conical seat by screws mounted in the cover. This resetting is necessary from time to time, since the soft material of the liner wears in usage. Even if the wear has progressed so far that finally the stopcock component contacts the metal surfaces of the cock housing, the sealing in the direction of flow is still sufficient. A further resetting of the stopcock, however, would restrict its rotary adjustability and might possibly result in seizing. As a rule, in this extreme reset position, there is no longer a reliable seal with respect to the stopcock shank. Because of the small conical slope at the stopcock seat, a relatively large reset path is required. Throughout this large reset displacement, the packing disk must be axially deformed between its outer and inner annular clamping location, so that it easily tears, or at any rate is damaged so that liquid may leak to the outside.
In another stopcock design with liner in accordance with U.S. Pat. No. 2,913,219, a packing is located between the stopcock shank and the wall fixed to the housing. However, it acts directly on the packing disk adjoining the stopcock bottom part, and, under pressure, may expand into an annular space provided at the top of this packing disk. Again, all reset forces are always transmitted to the stopcock bottom part, so that the aforementioned disadvantages appear; in addition, the packing material can easily relax and the sealing effect decreases continually.
It is, therefore, an object of the present invention to provide a stopcock of the initially described type in such a way that even with extreme wear of the liner, without a further resetting of the cock plug, leakage of liquid along the stopcock shank is reliably prevented during an extended period of usage.
Another object of the present invention is to provide a stopcock which may be economically fabricated and maintained in service.
A further object of the present invention is to provide a stopcock, as described, which has a substantially long operating life.